Investigation of a Cylindrical Ultrasound Phased-Array with Multiple-Focus Scanning for Breast Tumor Thermal Therapy

The purpose of this study is to investigate the feasibility of a cylindrical ultrasound phased-array with multiple-focus scanning strategy to produce a uniform heating for breast thermal therapy. In this study, a breast is surround by a 1-MHz cylindrical ultrasound phased-array consists of 200 elements with a radius of 10 cm and a height of 2 cm. To prevent overheating in the normal tissue, a scanning region of 1cm×1cm was selected as a single heating unit. Planning target volume (PTV) larger than this size would be divided into several sub-heating units, and then be treated sequentially with cooling phase to prevent overheating in the surrounding normal tissue. Parameters such as the target temperature, blood perfusion rate and the size of PTV are evaluated. Simulation results show that the target temperature affects the thermal lesion size and the blood perfusion rate increases the heating time significantly. This method provides efficient heating for breast tumor thermal therapy while preventing overheating the ribs.